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LED bar graph

Alright, I have been trying for the past couple of months to create this LED bar graph--the premise for the circuit was this: when the circuit was turned on, it would light up a 2x5 matrix of LED's in sequence, where after about 4 seconds, all of the LED's would be lit. I have considered having capacitors in parallel with each line of LED's so that the LED's acted as a sort of indicator as to how full the capacitor was....I had some trouble with that. If anyone can steer me in the right direction, I would appreciate it.

Thanks! grant

Reply to
ridiculoussyllablereplacement
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A couple of ideas,

The LM3914 is a single chip that might work for you. You can google for it or for LED bar graph and you should find example circuits. You would want to give this a triangle wave input that ramped up to maximum voltage in 4 seconds. An op-amp, a capacitor and a couple of resistors can help you create something like that.

The single chip microcontrollers could be programmed to do something like this. This is much more of a software approach to solving your problem. You would create a timing loop and have the program set the pins low and high to turn your leds on and off.

You can toss me mail if you want me to be more specific.

Reply to
Don Taylor 

--
View with a fixed-pitch font like Courier:
                                   

        7555                    +5v                              +5v
      +-------+       +-------+  |                                | 
   +--|TH    R|----+  |     D1|--+       ALL 2N4401               |
   |  |___    |    |  |       |                C-+-[270R]--[    Q1|--+--[1KR]-----B  |                |
   |  +-------+  | |  |       |  |         +---E +-[270R]--[
Reply to
John Fields 

--
Oops... The 7555\'s reset is low true, and for the symmetrical
astable TH should be connected to TR\\.  Also, any general purpose
small-signal NPN will work.  Orr get rid of the base resistors and
use 2N7000s.


                  +5v             
                   |              
                 [10K]             
         7555      |                +5v                         +5v
      +-------+    |  +-------+      |                            | 
   +--|TH  OUT|--+-|--|>    D1|------+   ALL 2N4401               |
   |  |__    _|  | |  |       |                C-+-[270R]--[
Reply to
John Fields

At the risk of sounding completely ignorant...I don't follow you. heh-- the 7555 could just be any 555 timer, I'm assuming...but what is the

74HC174 doing here?
Reply to
ridiculoussyllablereplacement

--- It's a shift register.

CLK Q1 Q2 Q3 Q4 Q5 Q6

---|----|----|----|----|----|---- 0 0 0 0 0 0 0 1 1 0 0 0 0 0 2 1 1 0 0 0 0 3 1 1 1 0 0 0 4 1 1 1 1 0 0 5 1 1 1 1 1 0 6 1 1 1 1 1 1

-- John Fields Professional Circuit Designer

Reply to
John Fields

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